In cellular communication networks, the mechanism of handover is a key feature for enabling the cellular properties of seamless mobility. In conventional cellular networks, with each base station operating a cell with a certain coverage, handover is performed when signal interchange with one base station is becoming weak and signal interchange is expected to be better with another base station. The interest in deploying low-power nodes (such as pico base stations, home eNodeBs, relays, remote radio heads, etc.) for enhancing the macro network performance in terms of the network coverage, capacity and service experience of individual users has been constantly increasing over the last few years. At the same time, there has been realized a need for enhanced interference management techniques to address the arising interference issues caused, for example, by a significant transmit power variation among different cells and cell association techniques developed earlier for more uniform networks. Thus, as so called heterogeneous cellular networks appear, i.e. where there are cells and base stations on different levels, the handover task becomes more complicated. Here, the terms macro cell and pico cell are used in this disclosure, although different prefixes, e.g. micro, femto, etc., may be used in the field, to denote the higher level and the lower level type of cells, respectively.
Conventionally, a UE associated with a cell operating on one frequency, but which may have better communication when associated with a pico cell operating on another frequency need to find a macro cell covering the pico cell attractive for handover, make handover to the macro cell, and then possibly finding the beneficial communication of the pico cell. It is therefore a desire to find an approach for improving mobility at least for such cases.